The discovery of the microwave background radiation in the 1960s provided cosmology and astrophysics with an exceptionally powerful tool for investigating the history of the Universe and the nature of massive objects within it. This lecture will tell the story of the microwave background radiation, from the original idea in the 1940s up to the most recent measurements from satellites in orbit and telescopes in Antarctica, and show what we have learned from the increasing degree of precision with which we can study the radiation.